title: The relevance of the radiological signs of acetabular retroversion among patients with femoroacetabular impingement.
abstract: Orthopaedic surgeons have accepted various radiological signs to be representative of acetabular retroversion, which is the main characteristic of focal over-coverage in patients with femoroacetabular impingement (FAI). Using a validated method for radiological analysis, we assessed the relevance of these signs to predict intra-articular lesions in 93 patients undergoing surgery for FAI. A logistic regression model to predict chondral damage showed that an acetabular retroversion index (ARI) > 20%, a derivative of the well-known cross-over sign, was an independent predictor (p = 0.036). However, ARI was less significant than the Tönnis classification (p = 0.019) and age (p = 0.031) in the same model. ARI was unable to discriminate between grades of chondral lesions, while the type of cam lesion (p = 0.004) and age (p = 0.047) were able to. Other widely recognised signs of acetabular retroversion, such as the ischial spine sign, the posterior wall sign or the cross-over sign were irrelevant according to our analysis. Regardless of its secondary predictive role, an ARI > 20% appears to be the most clinically relevant radiological sign of acetabular retroversion in symptomatic patients with FAI.
authors.affiliation: Rothman Institute at Thomas Jefferson University, Sheridan Building, 10th Floor, 125 South 9th Street, Philadelphia, Pennsylvania 19107, USA. claudio.diaz@rothmaninstitute.com
authors.forename: C
authors.initials: C
authors.lastname: Diaz-Ledezma
authors.forename: T
authors.initials: T
authors.lastname: Novack
authors.forename: O
authors.initials: O
authors.lastname: Marin-Peña
authors.forename: J
authors.initials: J
authors.lastname: Parvizi
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging*; D000293:Adolescent; D000328:Adult; D060751:Bone Retroversion / Q000000981:diagnostic imaging*; D005260:Female; D057925:Femoracetabular Impingement / Q000000981:diagnostic imaging*; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011859:Radiography; D055815:Young Adult
keywords: Acetabular retroversion; Acetabular retroversion index; Chondral lesions; Femoroacetabular impingement; Focal overcoverage; Hip preservation surgery